98 5.7 running rich

[mnstrburbon]

Ok so it has been running like crap for over a year. sofar had a tune up done and the swaped the following parts collant temp sensor,throttle body and they said injector spider un sure on that one and the 4 02 sensors. but it runs really ruff at idle and blows black smoke like abuilt diesel i mean you can literally not see the cars behind you. After it pours smoke and r come up it smoths out and picks up power.It is drivable as long as you cruise it if ya step on it it blows smoke acelerates and then kicks in.They are telling me the heads are bad?It has 230,000 on it and ran like a dream untill this started. it throws missfire codes on the right bank only thing i can think of is the fitting for the collant was tightened and i herd a small crack sound un sure if it cracked the manifold all the way through. And i cant remember if it started after that or not but it does not burn collant.

 

[bigblock72]

Fuel pressure regulator might be leaking, it'll cause misfires on passenger side and cause rich running as well.
Other possibilities include a MAF and a bad motor. It's hard to say without seeing it.

 

[mnstrburbon]

I checked the fuel presure by turning the key on it went to 40 ish IIRC and then fell off is it supost to hold presure or what? never got a straight answer from people.
Is the fuel pressure regulator in the intake or on top of it some where.
what is the maf and bad motor. Mass airflow meter or the map sensor
Map was changed form a good truck as well as all the other parts listed before.
thanks for the help i think it is fuel related it just runs to good to be major i think. I still pull my suburban and toy hauler with it its just gutless and i baby it to save it.

 

[bigblock72]

The fuel pressure regulator is inside the intake on the fuel spider assembly. When the regulator leaks it dumps fuel right into the back intake ports.

The MAF is the mass air flow sensor, they can go bad and skew the air flow reading and cause the same kinds of problems you are describing. It's fairly easy to tell with a scan tool if they are reading accurately or not.
Do you have an aftermarket air filter or air box installed?

IF the engine is weak or using oil or has a lot of blow by it'll cause all sorts of strange problems with the computer.
Is the intake elbow on the throttle body or the throttle body itself coated in oil from the breather hose?

 

[Thunder]

Was the engine running when you checked fuel pressure? If it built pressure then fell off you may have a leaking regulator Like BB72 said. With the engine idling the pressure should hold steady and not vary. Hard acceleration will make it go up a bit but it should not go down.

 

[mnstrburbon]

everything is stock on it.
I have a scanner and it only throws miss fires ill go scan it again and put the codes up.
They told me they changed the spider is the regulator a seperate part or part of the spider.
when i checked the fuel pressure it was not running ill do a running check on it today as well.

 

[bigblock72]

Check the short and long term fuel trims, also what the MAF is reading when you reconnect the scan tool.

The fuel pressure should stay up when the fuel pump shuts off, if it bleeds off then there is a leak somewhere.

Did they replace the whole spider assembly or just some injectors? The regulator is part of the spider assembly, but I've had them bad out of the box. The fuel trim numbers will tell me if their is a leaky regulator or injector(s).

 

[mnstrburbon]

i dont have a super fancy scan tool it is an auto exray dont know how to read the injector values on it i looked but there is no option for it that was my first thought to insure a leak.
they replaced the whole spider off a running truck along with the other parts listed in post 1.
fuel pressure is 50 at idle if you rev it it goes to 60 semms to hold constant no fluctuation.
here are the codes
P1153 H02S1 insufficent switches bank 2 sensor 1
P0174 system too lean bank 2
Po151 o2 sensor circuit low voltage bank 2 sensor 1.
Where excatly are the o2 sensors it has 4 i have changed them all if i recall atleast the 2 on the exhaust pipe on the 2468 bank. One closer to motor one at the cat.

 

[Thunder]

It looks to that #1 02 sensor on bank 2 is bad, has a short, or bad connector. That will be the sensor closest to the engine.
The sensor #1, up stream of the cat nearest the engine. Control air fuel ratio and engine management. The sensors #2, after the Cat simply monitor the function of the catalytic converter and wont cause the problems you are having.
From the codes it looks like the sensor is continually telling the ECM that that bank is running lean. ECM is richening up the mixture causing your rich mixture problems. Beings the sensor is always saying the mixture is lean the ECM keeps dumping more and more fuel.
First I would try replacing the #1 sensor on bank 2, inspect the wireing, ect.

 

[mnstrburbon]

I think i already changed it so maybe a wiring issue is there a fuse or some way to check the voltage what is it supost to be.
What if i swapped the sensor side to side and see what happens.
Thanks for all the help i just hate these fi motors some times.

 

[dyeager535]

You can swap side to side as long as the sensors are the same.

Cheaper way to diagnose the sensor than simply replacing.

From my buddies experience with his GM product, the O2 errors have always been caused by something else not working right.

 

[bigblock72]

You should be able to read O2 voltage with your scanner. The voltage should vary from around .2 volts up to .9 volts.

If the reading is good then your problem is not the sensor. If the reading is zero or doesn't ever go above .5 or so then the sensor could be weak, the heater in the sensor bad, poor connections, blown fuse for heater circuit etc.

I agree with Dorian, these sensors don't go bad very often and most of the time it's something else, especially when there are lean codes set. In your case though I suspect the sensor (even if it is new) and/or the the heater circuit and/or the O2 sensor heater fuse.

Try swapping a known good sensor as Thunder suggested and see what readings you get on the scanner.

 

[mnstrburbon]

ya no improvment before when i replaced it.. where would the fuses be for it in the engine compartment or under the dash. ill go out side right now and get the readings.

 

[mnstrburbon]

Hit the nail on the head no voltage at sensor 1 bank 2 it pluged in and the little clip is in there too. This sensor was replaced with a bosch one when the problem started guess i never reconfirmed it operation..
Checked all fuses on the driver fender well and all looked good.
Thanks for all the help whats the next step in checking voltage and what should it be.
Pull the wires and check for voltage with truck key on or running/
aand where would the fuse be for this if there is one.

 

[mnstrburbon]

So I unpluged the bank 2 sensor 1 and magically its all good runs like a top again no miss and the smoke seems to be gone it is night so cant comfirm 100% but runs alot better, So im guessing my new o2 was bad from the get or its a wiring game. Wish i would have done this a year ago when it started just been not driving it and dealing with it when i had too. Its smog time so thats why the rush to fix.
It had oil in the conector so maybe that caused it. The voltage un pluged was .475 iirc all other are fluctuating with in the specs given.Light came back on and only code now was 154 iirc no voltage change in that O2.
THANKS A BUNCH GUYS FOR ALL THE HELP SO FAR

 

[Thunder]

This sensor was replaced with a bosch one when the problem started guess i never reconfirmed it operation..

Bosch sensors are Crap. German engineering. There is a very good reason Germany lost WW2.
Much better to get a good Mexican made AC Delco.

 

[mnstrburbon]

Got an ac delco sensor values are reading no more engine light and runs like a dream thanks again to everyone for all the help.. Some times the siplest things.

 

[Thunder]